Why use iTunes at all when there are many free alternatives available
The following link list's 8 free alternatives.
http://www.ilovefreesoftware.com/27/featured/8-free-alternatives-to-itunes-for-windows.html
Well, for the same reason that regular computer users use Adobe Reader for PDF files instead of foxit...
They don't know any better!
Plus, they're big creatures of habit, so if you take away their precious iTunes after they've been using it for 2+ years and slap on something else, they'll just moan and complain until you put it back on for them.
arrgh... users. Sheep, I tell you. Sheep.